A should be the answer. We are asked to choose the answer which does not weaken, that is, any answer which strengthens or does not weaken is correct answer.

John observed that most people at Apex Health Club uses aerobic exercises machines instead of weight-training equipment. And, hence, he concluded that people are more likely to burn fat instead of increasing muscle mass. And again he concluded that since people do not like to increase muscle mass they do not consume the Blown's product, which helps to gain muscle mass. so, the advertisement at outside the Health Club, which is aimed to attract the members of the Health Club, is of no use since members are not inclined to increase muscle mass.

Choice A tells us that most club members work in nearby buildings whose exercise rooms have higher qualities aerobic machines, and although they come to the Apex Club. But the members are coming to club in early morning hours and not in work hours. And since they do not like to gain muscle mass, the advertisement is ill-conceived.

Please provide another explanation as this has taken 5 minutes.

Fame,
I will simply focus on (B). I will say, this is a very well-written question --- not a surprise from MGMAT! --- and it's a very difficult question. I think it's reasonably clear that (C) & (D) & (E) are weakeners, and I think (B) is the answer choice that makes this a very challenging question. Without careful reading, it's hard to see why this is not irrelevant.

Notice, the prompt was careful to specify ---- "In several months of going to the Apex Health Club almost every day in the early-morning hours, I have seen ..."
The evidence in this argument is entirely based on John's observations --- there's no objective source of information other than what John saw. Furthermore, all these observations were made in the early morning hours, presumably before the work day begins. John is vastly generalizing from what he sees at only one specific time of day.

Now, let's consider what (B) says.
Most members of Apex Health Club are aware that weight training is generally ineffective for individuals who have not consumed a pre-training meal 3 to 4 hours beforehand, while fat-burning exercise is most effective after eight or more hours of fasting.
Suppose these biological facts are true, and suppose the Apex users are well-acquainted with them. If fat-burning aerobics work best after 8+ hours of fasting, when would be the ideal time of day for someone with typical hours to do this? Early in the morning, right after waking up --- presumably, the exerciser wouldn't have eaten since dinner the night before, so that's more than 8+ hr. In fact, for most people, that's the only 8+ hour gap between meals in their day. Therefore, all the aerobic folks would have to show up at the crack of dawn, when John sees them.
By contrast, the weightlifting muscle-mass folks need to exercise 3-4 hours after a pre-training meal. Well, no one has their pre-training meal at 3 am! These folks would probably show up at the gym to do muscle-mass work either in the late afternoon (3-4 hours after lunch) or at night (3-4 hours after an early dinner). They would never show up at the gym at the crack of dawn, and therefore John would never see them.
This weakens John's argument. John is essentially saying --- everybody does aerobics and nobody weight-lifts. Well, that's very much true of the early morning crowd, the only slice of the population he sees, but it's not certainly not true of the other time-slots in the day when John is not in attendance. There are plenty of weight-lifters, just at other times of day that John doesn't see.

Does all this make sense?

Mike
_________________

Mike McGarry
Magoosh Test Prep

Very good Question and Very nice explanation Mike....Thanks